Technology update

Jun 10, 2008

Microwave cooks up zinc oxide nanowires

Nanotechnology experts at Cambridge University, UK, have shown that microwave heating is ideal for reducing the growth time of zinc oxide (ZnO) nanowires from several hours to a matter of minutes. The researchers observed average growth rates as high as 100 nm per minute using a commercially available 700 W oven.

Microwave heating has been used before by scientists to synthesize micron-sized ZnO particles, but Husnu Emrah Unalan and his colleagues have taken the method a step further by growing ZnO nanowires on a range of substrates including silicon, glass and PET. The large-area technique is expected to open up applications ranging from LEDs to antireflective coatings.

"Large area synthesis is possible with other methods, such as chemical vapour deposition, but this requires a much higher level of technical complexity," Unalan told nanotechweb.org. "Our system is very straightforward."

To grow their ZnO nanowires, the researchers place a seeded substrate in an aqueous solution of zinc nitrate hexahydrate and hexamethylenetetramine and then heat the set-up in a domestic microwave for 1–30 minutes.

As well as being quick to produce, the microwave-grown nanowires appear to have fewer defects compared with furnace grown material, which could benefit future devices.